Pathology of Emphysema

IN THIS Cardiff Symposium of the Postgraduate Medical Journal, I should first explain why the Pathology Department of the Welsh National School of Medicine became interested in emphysema as one of its main subjects for research. It arose out of a study of thousands of respiratory cripples in the coal mining industry. In the early part of this century coal miners were a healthy population apart from accidents, but by the third decade it was evident that respiratory disease of serious proportions was arising. At first it was thought that this was silicosis (Cummins and Sladden, 1930), affecting those miners who were exposed to rock dust as well as to coal. It soon became evident, however, that although there were cases of silicosis in those who worked especially on rock, there was a far higher incidence of respiratory troubles in miners who worked on the coal seams and in coal trimmers who load coal into ships. The name "coal worker's pneumoconiosis" was applied and is now accepted in law. A study of the lungs of miners showed that there are two quite separate forms of pneumoconiosis (Gough, 1947). The one is a massive fibrosis while the other consists of discrete nodules of coal with comparatively little fibrosis but which subsequently become surrounded by a characteristic emphysema now known as "focal dust emphysema". A technique was evolved to demonstrate this emphysema more effectively. This is the whole lung paper section method devised by Gough and Wentworth (1957/58; 1960). It is carried out on lungs fixed in expansion. The large section method was next used for a study of respiratory diseases of the general population and it revealed (Gough, 1952) two fundamentally different forms of emphysema. In the one there was a selective involvement of the centres of the lung lobules. This is known as central or centrilobular emphysema. In the other form there was no selection of the kind of air spaces dilated and since this lesion was not based on the lobule but often affected the greater part of both lungs it was referred to as generalised but this name was not sufficiently precise and the condition is now known as "'panacinar" or "panlobular". In view of the common use of the terms lobule and acinus in the classification of emphysema, it is necessary to define them.